Vascular stent prototype: results of preclinical evaluation

Vascular stent prototype: in vivo swine studies

PURPOSE

Evaluation of implantation technique and biocompatibility of a new balloon-expandable peripheral vascular stent.

MATERIALS AND METHODS

Twenty-four stents, varying in diameter from 4 mm to 14 mm and length from 2 cm to 6 cm, were placed in eight microswine. After implantation, two of the animals were killed at 2 months and the remaining animals were killed at 6 months. All animals underwent premorbid angiography. The stents were then pressure fixed, harvested, and encased in methacrylate. The specimens were then sectioned by a diamond saw prior to staining. Individual specimens were then photographed, projected against a screen, and the neointimal thickness quantified by calibration with the diameter of the stent wire retained in the specimen.

RESULTS

Technical success (implantation) was 96% (one embolization). All stents were widely patent at 2- and 6-month follow-up. Histopathologic examination demonstrated a very thin neointima covering the stent wires, with a maximum thickness measuring 254 microns.

CONCLUSION

This new stent is safely implantable and biocompatible as tested in the arterial system of this animal model. Human clinical trials are indicated.

Prototype stent: in vivo swine studies in the biliary system

PURPOSE

To evaluate the safety of implantation and the biocompatibility of a new balloon-expandable stent in the biliary system of the swine model.

MATERIALS AND METHODS

Thirty stents, varying in diameter from 4 mm to 12 mm and in length from 2 cm to 6 cm, were placed in the bile ducts of 10 microswine. After implantation, one-third of the animal subjects were killed at 2 months and the rest, at 6 months. All animals underwent premorbid cholangiography. Stents were pressure fixed, harvested, and encased in methacrylate. Specimens were then sectioned with a diamond saw, prior to staining. Individual specimens were photographed for visualization of the histologic reaction.

RESULTS

Technical success (implantation) was 100%. All stents were widely patent at 2-month and 6-month follow-up. Histopathologic study demonstrated a very thin epithelial hyperplasia that formed between stent wires. This did not cover the stent wires.

CONCLUSION

This new stent is safely implantable and demonstrates minimal tissue reaction in the biliary system of the swine, when compared with other metallic biliary stents.